Conductive plastic moldings obtained by imparting electrical conductivity to plastic moldings have advantages of moldability, light weight, and the like and have recently been utilized in a broad range of application, such as electromagnetic wave shields, antistatic materials, plane heaters for room heating, etc. The application range tends to be further broadened.
Known techniques for imparting conductivity to plastic moldings include compounding of a conductive substance, e.g., carbon black, metal powders, metallic fibers, etc. into a resin molding material, application of a coating containing a conductive substance to a resin molding, adhesion of a metal atom to a resin molding by ion plating or sputtering, and the like. In addition, various attempts have been made to render the resin per se electrically conductive.
However, these conventional techniques have their respective disadvantages as described below, and the resulting products are not always satisfactory depending on use.
According to the method of dispersing a conductive substance in a resin before molding to obtain a conductive resin molding material, achievement of satisfactory conductivity requires a large quantity of the conductive substance to be compounded, which leads to adverse influences on molding properties of the resulting mixture and physical properties of the resin.
The method comprising applying a coating having incorporated therein a conductive substance onto a resin molding encounters difficulty in uniformly applying the coating particularly on a molding of complicated shape. Besides, the conductive layer formed on the surface of the molding is apt to fall off during long-term use.
The method comprising adhesion of a metal atom to the surface of a resin molding requires a special apparatus to carry out to thereby increase the cost.
Further, none of the so-far proposed resins showing conductivity by themselves have been put into practical use due to their poor molding properties.
On the other hand, in the filed of portable storage batteries including lead accumulators which are utilized as auto batteries, there are many problems in handling and transportation because a fluid, such as dilute sulfuric acid, is employed as an electrolyte liquor.
In order to solve these problems, various attempts have been made to fix the electrolyte liquor. For example, there have been proposed a method of impregnating an electrolyte liquor into voids of glass cloth and a method of incorporating a gelling agent to an electrolyte liquor. These proposals, however, are still unsatisfactory as fixation or retention of the electrolyte liquor is insufficient and also the cell to be used is limited in shape and volume. Therefore, it has been keenly demanded to develop an effective method for fixation of an electrolyte liquor for portable storage batteries.